He then placed a hand through the machine's unguarded opening to move the log and the device started up again.
Four of the worker's fingers were then severed. Three were later successfully reattached in hospital.
However, the court was told the grip in his dominant hand was weak and had little feeling, including being able to tell if an object was sharp or dull, or hot or cold.
A WorkSafe investigation found the machine was not designed and manufactured to meet the appropriate health and safety and industry standards.
According to WorkSafe, it wasn't adequately guarded and did not have safety features such as interlocks and a locking safety latch.
Despite having been aware of these failures MMD Engineering still allowed the machine to be installed at Davies Tree Service's site, Worksafe said.
The WorkSafe probe found Davies Tree Service had removed what guarding was installed from the machine.
WorkSafe's chief inspector of investigations Steve Kelly said both companies' offending was "significant".
"MMD Engineering in accepting the work from Davies should have ensured that it knew and understood and implemented health and safety and industry standards for the safe design of machinery," he said.
"Likewise, Davies should have ensured that the machine met guarding and safe use of machinery standards prior to being put into operation. When issues arose with the guard door Davies should have addressed these matters with MMD rather than taking matters into its own hands and removing the guard.
"Had proper precautions been taken, this worker would not have suffered from injuries which will impact him for the rest of his life."